This invention is directed to a radiation-hard, non-volatile planar film memory fabricated by silicon integrated circuit processing. To be described is a memory cell construction which provides coincident current switching and high stability of stored information, based on flux closure and magnetoresistive readout.
In applicant's copending application Ser. No. 384,681 filed on June 3, 1982, entitled "Magnetoresistive Sensor with Enhanced Response and Reduced Bias Field", and assigned to the same assignee as the present invention, there is described a sensor for the detection of external magnetic fields by the use of a thin film magnetoresistive sensor strip located in the gap of a much thicker high permeability magnetic flux concentration film. The flux concentrator greatly increases the magnetic field sensitivity of the magnetoresistive sensor through the flux gathering capability of the thicker flux concentrator film. The copending application is not directed to a magnetic memory.
In the present invention there is described a novel random access memory (RAM) structure in which a magnetoresistive film sensor is positioned in the gap of a thicker film magnetic circuit, the magnetic circuit including at least a memory film and preferably also including a flux concentrator film adjacent the magnetoresistive film.